What the record shows for Guam
The strongest earthquake on record near Guam is a magnitude 7.8 in 1993, centred 32 km S of Inarajan Village, Guam - 33 years ago. The event is catalogued by USGS. See the event record.
Over the last 20 years, USGS has catalogued 2,853 earthquakes of magnitude 4 or greater within 300 km of Guam - roughly 143 a year. That rate describes how often the ground moves enough to be recorded, not how often damage occurs; most of these are never felt.
The NOAA NCEI database records 8 tsunamis within 300 km of Guam between 1767 and 1993. The most significant was in 1909 near Guam, Mariana Islands, triggered by an M8.0 earthquake.
7 volcanoes are catalogued near Guam, including Seamount X, Forecast Seamount, NW Rota-1, Esmeralda Bank, Mariana Back-Arc Segment at 15.5°N, Ruby and 1 more. Volcanic systems generate their own earthquake swarms, which is why activity here can look different from a purely tectonic region.
Sources: USGS earthquake catalog, NOAA tsunami database, and the Smithsonian Global Volcanism Program. Figures update as the catalogs are revised.
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Guam sits beside the Mariana Trench, the deepest place in the ocean, and feels frequent offshore earthquakes.
The only real protection is a warning the moment the ground moves - which is exactly what the free QuakeMate app gives you, along with tsunami and volcano alerts for Guam.
Earthquake risk in Guam - FAQ
Is Guam at risk of earthquakes?
Yes. On average about 143 quakes a year nearby of magnitude 4+ within 300 km, based on the last 20 years of USGS data. The strongest earthquake on record nearby is M7.8 in 1993.
What was the biggest earthquake in Guam?
The strongest earthquake on record near Guam is M7.8, in 1993 (32 km S of Inarajan Village, Guam), from USGS.
Does Guam get tsunamis?
Yes - 8 tsunamis since 1767 (most recently 1993) within 300 km, from the NOAA database.
How do I get earthquake warnings in Guam?
Download the free QuakeMate app for iPhone. It watches your location and sends a real-time push the instant a quake strikes nearby, plus tsunami and volcano alerts, with custom magnitude and distance rules. On Android, join the waitlist.